Generally, heating a swimming pool, hot tub, etc., represents the single biggest recurring operating expense facing the owner. Various types of lightweight, buoyant, multi-layer swimming pool covers exist in the prior art which serve multiple purposes such as retaining as much of the water's heat as possible, preventing or minimizing evaporation of the water over time, and keeping dirt and other debris out of the pool. Often the pool covers are placed on the pool, more often than the pool is actually used by the owner, especially for pools that are outdoors, where the cover remains on the pool for extended periods of time. One of the lightweight, multi-layer covers of the prior art has a thermoplastic top layer, the top layer having integral insulative air pockets which act to trap and focus the solar heat into the water. This top layer is suitably joined or otherwise bonded to a thermoplastic bottom layer, the two layers forming the cover. During the solar heating of the water, this particular cover allows the light to pass through the cover to heat the water, but does not reflect heat down into the water. Also, during the solar heating the insulative air pockets act as individual solar prisms, the effect of which is to heat the interior air within each insulative air pocket, thereby allowing a total insulation barrier to be effectuated for the whole cover. Consequently, it would be an advantage for a lightweight, multi-layer, reflective swimming pool cover to have the ability to provide solar heating of the pool during the day utilizing an additional reflective thermoplastic layer, thereby improving the efficiency of the cover during use, without increasing the number of layers or weight of the cover. And it would also be a further advantage if the cover would also be able to provide the insulative feature for the pool during the night hours, thereby using the reflective layer to continually reflect radiating heat back into the water, both features acting in concert to reduce the operating expense that is associated with the heating of the pool somewhat over time.
Depending on the size of the pool to be covered, the costs of the various types of lightweight multi-layer covers in the prior art are relatively expensive to purchase. It would be an advantage in the art if a swimming pool cover could be made relatively inexpensively utilizing long-lasting lightweight thermoplastic film layers, yet having features like reflective integral air-pockets for reflective solar heating and insulation, which other more expensive covers do not have.
The present invention overcomes these and other problems inherent in existing lightweight, multi-layer covers for swimming pools and the like. The present invention combines a heat reflective layer with an insulative layer which improves the effectiveness of the cover without significantly or materially increasing the thickness or weight of the cover.